The Three-Domain System EUKARYA BACTERIA Fungi Animals Cellular Mitochondrion slime molds Oomycotes Plants Cyanobacteria Amoeba ARCHAEA Gram-negative Extreme Ciliates bacteria halophiles Chloroplast Methanogens Chromista Euglenozoa Plasmodial Gram-positive Hyperthermophiles slime molds bacteria Microspora Thermetoga Archaezoa Universal ancestor Figure 10.1 The Three-Domain System Figure 10.1